If a person with a dragonmark becomes an undead, would their dragonmark still be active/under their control?
Because if so, I have a pretty amazing story lined up… By canon lore, dragonmarks don’t work for undead. This is a crucial part of the story of Erandis Vol, who’s the last bearer of the Mark of Death but can’t use her in her undead form.

— Keith Baker (@HellcowKeith) November 1, 2020